A qualitative and quantitative analysis of the amount of myocardial scarring and the degree and extent of coronary arterial narrowing by atherosclerotic plaque in the entire lengths of each of the 4 major epicardial coronary arteries is described in 18 necropsy patients with healed transmural myocardial infarcts and death from a non-cardiac condition. Of 924 five-mm segments examined in the 18 study patients, 292 (31%) were 76-100% narrowed in cross-sectional area by atherosclerotic plaques (controls equals 5%); 319 (35%) were 51 to 75% narrowed (controls equals 34%); 211 (23%) were 26 to 50% narrowed (controls equals 44%, and 102 (11%) were 0 to 25% narrowed (controls equals 17%).